Chapter 18 – Evolution and the Origin of Species (Vocabulary Flashcards)

60 vocabulary flashcards covering evolution, natural selection, evidence, species concepts, and historical context.

Evolution

Change in organisms across Earth's history; modern species descended from earlier life.

Not evolution in individuals

Evolution is not: individuals evolving, purposeful change, or a completely random process.

Descent with modification

All life shares a common ancestor and lineages change over time.

Natural selection

Mechanism by which evolution occurs: differential survival and reproduction based on heritable variation.

Variation

Differences among individuals in traits.

Overproduction

More offspring are produced than survive, creating competition.

Differential survival and reproduction

Individuals with favorable traits survive and reproduce more than others.

Adaptation

Heritable traits that increase survival and reproduction in a specific environment.

Common ancestor

The original ancestral lineage from which different species diverge.

Fossil record

Direct evidence of past life; documents evolutionary history and transitions.

Transitional forms

Fossils showing intermediate traits between groups (e.g., whales).

Homologous structures

Traits in different species that arise from a shared ancestry.

Developmental homologies

Embryonic similarities among related species.

Vestigial structures

Remnants of ancestral traits that are reduced or unused in current organisms.

Convergent evolution

Unrelated species evolve similar traits due to similar environments.

Biogeography

Distribution of species reflects geographic history and history of isolation.

Molecular biology evidence

DNA, proteins, and genetic code support common ancestry; strongest evidence for evolution.

Morphological species concept

Species defined by physical appearance and structure.

Ecological species concept

Species defined by ecological role or niche.

Phylogenetic species concept

Species defined by ancestry and genetic relationships.

Biological species concept

Species that interbreed and produce fertile offspring; reproductively isolated.

Reproductive isolation

Barriers that prevent interbreeding between species.

Prezygotic barriers

Barriers that prevent mating or fertilization before zygote forms.

Postzygotic barriers

Barriers that reduce viability or fertility of offspring after fertilization.

Temporal isolation

Mating or flowering occurs at different times.

Habitat isolation

Species occupy different habitats and rarely meet.

Behavioral isolation

Different mating signals or behaviors prevent interbreeding.

Mechanical isolation

Incompatible reproductive structures prevent fertilization.

Gametic isolation

Gametes fail to unite or fertilize despite contact.

Hybrid inviability

Hybrids fail to develop or survive.

Hybrid sterility

Hybrids are viable but infertile (e.g., mule).

Hybrid breakdown

Hybrids are viable or fertile, but subsequent generations decline.

Allopatric speciation

Geographic isolation leads to population divergence and speciation.

Dispersal

Movement of individuals to a new area, initiating an isolated population.

Vicariance

Geographic barriers split a population into separate groups.

Adaptive radiation

One ancestor diversifies into many species in new environments.

Sympatric speciation

Speciation without geographic separation; often via sexual selection or niche differentiation.

Sexual selection

Selection for traits that improve mating success, driving divergence.

Habitat differentiation

Species diverge by specializing in different habitats or resources.

Polyploidy

Having extra sets of chromosomes; common in plants and can cause instant speciation.

Autopolyploidy

Polyploidy arising within a single species.

Allopolyploidy

Polyploidy arising from hybridization between species.

Rates of speciation

Patterns of how quickly new species arise; debated as punctuated vs gradual.

Punctuated equilibrium

Rapid evolutionary change followed by long periods of little change.

Gradualism

Slow, steady divergence over time.

Aristotle

Fixed species; believed in a linear ladder of life (scala naturae).

Scala naturae

Ladder of nature; hierarchical, unchanging organization of life.

Buffon

Early thinker who suggested species could change over time.

Linnaeus

Father of modern taxonomy; developed classification and binomial nomenclature.

Hutton

Geologist who proposed deep time and slow geological processes.

Lyell

Promoted uniformitarianism; earth’s features shaped by gradual processes.

Lamarck

Proposed use and disuse and inheritance of acquired traits (incorrect).

Use and disuse

Traits altered by use or disuse could be inherited (Lamarckian idea).

Inheritance of acquired traits

Traits acquired during life passed to offspring (Lamarckian idea).

Darwin’s two main ideas

Descent with modification and natural selection as the mechanism.

Observation: Variation exists

Darwin observed that individuals vary in traits within populations.

Observation: More offspring than survive

Competition for limited resources leads to differential survival.

Inference: Advantageous traits survive

Individuals with favorable traits are more likely to reproduce.

Inference: Favorable traits accumulate

Over generations, advantageous traits become more common.

Limitations of Darwin's theory

Does not explain origin of life, source of variation, inheritance mechanisms, or abrupt fossil changes.